While playing the game, press ~ to display the console. Enter "sv_cheats 1" to enable cheat mode. Then, enter one of the following console commands and press [Enter] to activate the corresponding cheat function:

Result

Cheat Code

Invincibility

god

999 health

health 999

All weapons with full ammunition

impulse 101

Ignored by enemies

notarget

No clipping mode

noclip

"All weapons with full ammunition" code from: jah2331b

Cross eyed fish

In the levels after Riddick leaves in his submarine and the base is on self destruct, you will eventually reach a point where you crossed through water before. Go back into the water and find the point where you first dropped in and there is no ladder to climb back out. There is a secret box in the area. Swim to the upper right corner in the water and you will see a cross eyed fish.

Grenades

If an enemy throws grenades at you, you can throw it back by pressing E. However, grenades have a small blast radius -- so you may not be in as much danger as you think.

Vending machines

At any vending machine, press any button rapidly and a health canister will drop out. This can be done twice. However after this, a live grenade will come out and endanger you, unless you throw it back or run away.

Defeating the first Boss

Use the following trick to defeat the large monster in the wooden area. Drop to the right immediately after you enter the pit. Let him charge at you until he is in the corner. Stun him with the pistol, then run back to where you started. There should be a flammable barrel nearby. Shoot it and try to catch him on fire. This deals great damage, and you should only need several more pistol shots and a couple shotgun blasts to finish him off.

Defeating soldiers

Soldiers are a tough enemy to defeat at first. An easy way to defeat them is to get very close with the shotgun, usually touching them. However, if done on a long strip of land with no cover, you will not survive long. Try to hit them in the head with the pistol, or spray just above their head with the rifle while zoomed.

When you get in the car after navigating the maze after the monster, you must defeat two supers and a few regular soldiers before you get out. Instead of getting out and losing a lot of health, close the window and start throwing grenades without standing up. This is an easy way to kill all the soldiers, or set them on fire.